It was the largest acquisition for a venture-backed software company started in the city since 2005. The hope was that it would spur new investments, in part by the people who profited from the deal, in a sort of virtuous cycle that tends to work in the venture capital world.

Some of that scenario has started playing out. Union Square Ventures, a backer of Tumblr, recently raised two funds totaling $350 million.

And now David Karp, Tumblr’s founder and chief executive, has started making some investments.

As Venture Capital Dispatch reported on Monday, Mr. Karp put $500,000 into Sherpaa Inc., a New York startup that serves Tumblr’s staff and about 80 other companies in New York with its app that connects employees to physicians. Last year, Mr. Karp also backed Superpedestrian Inc., a Boston-based maker of a device that helps transform standard bicycles into hybrid electric ones.

Mr. Karp said he made a few other investments but declined to name them. Still, this is not an indication he is barrelling into investing, he said.

“I’m not trying to become an angel investor. And I have no aspiration to become a venture capitalist,” Mr. Karp said. “But insofar as I can give to this community, to support my friends, I’m very happy to.”

To make the investment in Sherpaa, Mr. Karp had to get approval from Yahoo’s ethics board, but he said the company isn’t holding him back too much. “I can’t do anything competitive, is the big thing. There’s nothing off limits about medical startups or bicycle wheels. But I’m not investing in any search engines,” he said.

It might not be just money that matters in the build-out of a robust New York startup community, Mr. Karp said. “More people have not just money, but wherewithal,” he said.

Tumblr, Kickstarter, Etsy and other high profile New York startups are holding engineering and other events to share knowledge with the rest of the community, he said.

The New York startup community has a different culture from Silicon Valley’s, Mr. Karp contends. Everyone in Silicon Valley is trying to recruit each other, for example.

“It’s so hyper-competitive,” he said.

In New York, startups “are in the shadows of big media, big finance. It makes the technology community a lot more humble, and a lot more supportive of each other.” What matters, he said, is to give back to a community that supported him in the early days.

The startup sector in New York is growing fast. New York State companies attracted $3.13 billion in venture investment in 2013, up from $2.19 billion in 2012, according to Dow Jones VentureSource. The 2013 number is the second highest since 1992, when data collection began, preceded only by 2000, when venture capitalists put $5.68 billion in the state’s companies.

What makes a difference in the development of a startup center, Mr. Karp said, is not so much “one person’s ability to write a check,” but getting New York on the radar of big venture firms.

“It means more folks from the companies out west, more of the investors spend time out here. With Tumblr, we had two very prominent institutional investors from California, from Sequoia and Greylock, out here for board meetings. They were coming to New York every couple of months. When they made the trip, they would meet with other startups,” Mr. Karp said.

Some firms are shifting more to New York, as in the case of Flybridge Capital Partners, which as Venture Capital Dispatch wrote on Monday, is tacking to New York, and now has three of its five investment team members based here and the rest in Boston.

About a year ago, Benchmark General Partner Bill Gurley complained that New York companies tend to sell too quickly instead of waiting for a big exit, through an IPO especially. It remains to be seen whether this year will be different, but it’s clear that there is a crop of New York startups that have taken late-stage capital recently, including MongoDB Inc., which raised $150 million, and AppNexus, which got $75 million last year. If they are successful, the virtuous cycle might get a boost.

About Venture Capital Dispatch

Produced by the editors of Dow Jones VentureWire, Venture Capital Dispatch tracks the fast-moving developments at the intersection of high-tech innovation and venture capital finance. Featuring the VentureWire reporting team in the Silicon Valley, New York, Boston and Shanghai tech centers, Venture Capital Dispatch provides insight into the newest start-ups and latest trends in venture capital investing. Write us at VCdispatch@dowjones.com. For more information on Dow Jones products covering venture capital and other financial markets, go to http://pevc.dowjones.com.